Zynga’s poor debut on the stock market continued in its second day of trading Monday, with the company losing nearly a further 5 percent off its initial public offering price.

The San Francisco online gaming company, which generates most of its revenue from games on Facebook’s social-networking platform, sold 100 million shares at $10 apiece Friday, raking in $1 billion and valuing the company at $7 billion.

However, the stock price began falling almost immediately after hitting the open market, and shares ended down 5 percent at $9.50. That pattern didn’t change Monday, as Zynga stock slid to a closing price of $9.05, a loss of $0.45, or 4.7 percent.

Zynga’s stock is probably hurting from a large offering and increased competition, analysts said Friday.

The 100 million shares Zynga offered represent 15 percent of the company, a much larger offering than other recent tech IPOs such as LinkedIn, Groupon and Jive, which all offered less than 10 percent. That decision led to the inability of individual investors excited about the stock to raise the price, said Sam Hamadeh, CEO of PrivCo.com, which compiles financial data on private companies.

The offering “was too big to move,” he said.

Meanwhile, more established video game companies, such as Redwood City’s Electronic Arts (ERTS), are moving in on Zynga’s dominant role in the social gaming category.

“The competition has game now,” said Jeff Matthews, a veteran money manager who doesn’t have a stake in Zynga. “(Zynga’s) product momentum probably peaked last year.”

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